1. Field of the Invention
The present invention is generally related to image processing, and, more particularly, is related to a system and method for processing video data.
2. Related Art
Many of the current video standards typically rely on a block coding scheme. For instance, MPEG-2 video compression is based on the block-based transform coding method which comprises block based temporal prediction, block based discrete cosine transform (DCT) processing, block based quantization, and entropy coding. The block based quantization may introduce distortion (e.g., coding artifacts) to a reconstructed image. That is, such coding artifacts, which include blocking artifacts and ringing artifacts, may be introduced to the decoded image from the quantization process. The quantization is basically a lossy compression process applied to DCT coefficients. The blocking artifact is caused by information loss of the low frequency DCT coefficients. Because the low frequency DCT coefficients are highly correlated across blocks, the loss in the low frequency coefficients breaks the correlation and it appears as abrupt changes of pixel values across block boundaries. The ringing artifact occurs when an image block has an obvious edge pattern and its high frequency DCT coefficients are degraded. The ringing artifact spreads out to flat regions within the block near the edge.
Various methods have been employed in the past and present to address such coding artifacts. Unfortunately, such methods, in general, either addressed one of the coding artifacts only, or had application only to still pictures (versus video).